Protection of electric apparatus



q 1,642,402 p 13,1927" M. BUCHHOLZ PROTECTION OF ELECTRIC APPARATUS Original Filed Sept. 15. 1922 ln ven for; fiaxBac/z/w/z Patented Sept. 13, 1927.

' UNITED-i STATES PATEN O F C rao'rao'rron or nmac'rarc arrana'r'ns Driginal application filed September 15,1922, Serial No.' 588,457; and in Germany April 10, 1922. Divided and th'iu'application flled April is, 1925., seriai' ivo. 23,675.

My invention has reference to a method and means for protecting electric apparatus erating in an insulating liquid, such as 011 transformers, oil switches, grounding 6 throttling coils, resistances and the like, and

it is one of the important objects of my invention to provide a device of very simple construction and great reliability, and adapted to operate before extensive injuries 10 to the apparatus to be protected can occur by sparking, overloading or other disturbances.

- My invention is particularly based on the fact that in the case of disturbances in the operation of the apparatus to be protected or in the case of sparking or other irregularities of operation, or whenever such irregularities are imminent, as well as in the case of any ebullition or fermentation processes in the oil, serving as an insulating liquid, bubbles of gases of decomposition are formed which can operate a protective means, for instance an electric contact, either a working or a closed contact, which is adapted to switch out of circuit the apparatus to be protected, or which will operate an alarm or 'annunciator device indicating the disturbance, or which is adapted to efiect both kinds of operations. The gases formed by decomposition may influence the protective means in different ways, this application being a division of my copending application Serial Number 588,457 filed September 15, 1922.

I may for instance utilize a variation of the pressure in the insulating liquid occurring in consequence of the unnormal condi tions of working mentioned above to vary the operative conditions of the protective circuit.

A protective device embodying this invention 18 illustrated in the drawings annexed to this specification by way of example in a purely diagrammatic manner in elevation.

In the drawings a is an oil filled transformer casino. 6 is the core of the trans.- former, a are the windings, (l are the leading-in insulations for the conductors. B is an alarm inserted in the rotective circuit supplied with current by t e source of current 9. k are the terminals of the protective circuit facing a diaphragm A mounted in the side wall of the transformer casing a and capable of bridging the terminals and closing the protective circuit whenever an increase of pressure within the casing aforcesthe diaphragm Aoutwards: Obviously, even a very insignificant increase of pressure within the casing a, due to an unnormal operation of the transformen'which results in'the generation of heat or liberation of gases or vapors within the insulating liquid, will suffice to force the diaphragm A outwards and against the terminal contacts is, thereby actuating the alarm B, which may however also be replaced by some other annunciator or by an oil switch or the like for throwing out of the transformer.

The circuit to be controlled by the contacts referred to may excite either directly or by the medium of an intermediate relay the releasing coil of an oil switch which interrupts the endangered circuit. In the case of apparatus the circuit of which does not include an oil switch, as fre uently occurs, for instance in the cases o transformers mounted in the field at wide distances apart, other provisions should be made for the purposes of this invention.

Besides the form of construction hereinshown and described, the invention is susceptible of a variety of other modifications and forms of application of the principle of my invention all of which operate substantially in a similar manner. The means of connecting the contacting device with the releasing circuit and the switching means are open to changes and alterations without any material importance for the operation of the apparatus according to my invention which in its broad aspects comprises the operation of safety devices for electric apparatus or the like, adapted for operation by vapors,

fumes, gases or similar emanations liberated and expelled from the insulating medium, and means adapted to be operatively influenced by such emanations, and connected to fuses or equivalent safety means, the instrumentalities shown and described in this specification as embodiments of these principles bein susceptible of modifications with out deviating from the spirit of my invention as set forth in the claims.

In the claims the term ases is meant to comprise also vapors and umes.

I claim 1. Protective system for liquid-insulated electric ap aratus comprising a container and a supp y of insulating liquid, surrounding the apparatusto be protected, aprotective circuit and means adapted to be operated by a variation of pressure occurring in the insulating liquid m cons uence of a decomposition of such li uid, or varying operated byv a deformation of said wall for d'ecom varyingthe'operative conditions of said circuit.

3. The method of controlling abnormal working conditions of liquid insulated electric .apparatusrwhich comprises causing a sitionoccurrin in the insulating liquid in consequenceo such abnormal conditions to vary the pressure in said liquid, and causing such variation of the pressure to varythe operative conditions of a protective circuit. p

In testimony whereof I aflix my signature.

MAX'VBUCHHOLZ. 

